[BUG] Claude settings JSON schema does not contain `sandbox.failIfUnavailable`

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

The sandboxing documentation contains:

To make this a hard failure instead, set sandbox.failIfUnavailable to true.

But the settings schema does not currently document this field.

We are maintaining an organisation-wide managed settings file in a git repo, and our CI check validates the file against the settings schema to make sure we don't cause issues (invalid file, or worse, intended change has no effect) when people raise MRs into the settings file. We currently cannot add this setting because it is absent in the schema.

What Should Happen?

Update the schema.

Error Messages/Logs

N/A

Steps to Reproduce

N/A

Claude Model

None

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.128

Platform

Anthropic API

Operating System

macOS

Terminal/Shell

Terminal.app (macOS)

Additional Information

_No response_